Spark plug



H. CARTNIILL.

SPARK PLUG.

APPLICATION FILED mic. 9, 1920.

Patented Sept. 2, 1922.

Patented Sept. 12, 1922.

UNITED STATES HoLLEY cammina., or sroxann, wasnmc'ron.

SPARK PLUG.

Application led December 9, 1920. Serial No. 429,477.

To all 'wlw/mit may comer/n.:

Be it known that I, HOLLEY CABTMILL, a citizen of the United States, residing! at Spokane, in Spokane County and State of vWashington, have invented certain new and useful Improvements in Spark Plugs,l of which the following is a specification.

The present invention relates to improvements in spark plugs for internal combustion engines, and contemplates a device of this character so constructed as to enable an inspector to ascertain the working conditions existing within the cylinder of the engine, and possessing features whereby the electrodes and adjacent parts of the plug Within the cylinder are maintained free from accumulation of carbon, &c., thus providing for the dual purpose of a test plug and an electrode cleaner.

The primary object of the invention Ais the equipment of standard or other forms of spark plugs with means whereby a' portion of the fuel mixture may be withdrawn from the interior of the cylinder, for inspection, and in so constructing this sampling means to form an auxiliary or delayed miniature explosion Within the spark plug by means of which a continuous succession of blasts of gas is blown over the electrodes and adjoining parts of the plug, thus preventing accumulation of carbon and eliminating the Vundesirable conditions resulting from such accumulation. y

With the above objects in view the invention consists in certain novel features of construction of the Vplug shell within the cylinder involving explosion pockets, and combinations and arrangements therewith of a testing plug, as will be hereinafter more fully pointed out and claimed.

In the accompanying drawings I have illustrated one complete example of the physical embodiment o my invention,comb1ned and arranged with a standard form of spark plug, according to the best m'ode I have thus far devised for the practicaly application of the principles of my invention.

Figurev 1 is a vertical centralV sectionalview through-Aa spark plug and the elements combined therewthformlng Ythe .subject matter of my invention.

Figure 2 is a 'view elevation of the spark plug, partly broken away for convenience of illustration.

Figure 3 is a bottom end viewof the spark plug and connections.

. the fuel charge In the preferred form of the invention as illustrated in the drawings .I have utilized a standard form of porcelain spark plug 1, which, is provided with a metal thimble 2, which latter is threaded as usual intothe walls of the engine casing of an internal combustion engine, and the plug is locked in the shell or thimble by means of the lock nut or jam nut 3 of usual type.

At its lower end the metal thimble is provided with an inner cylindrical bore 4 into which the tapered end of the plug, as 5 projects, and the stem or rod 6 of the plugV which extends through the plug from end to end is provided with the usual binding nuts 7 for the wire terminals of the sparking circuit, not shown. The electrodes 8 and 9 at the lower end of the stemp form the spark plug points for the spark gap or ignition medium and these elements, as shown in Figures 1 and 2 are located below the thimble or shell to project the required distance in the engine cylinder for igniting therein. l

The lower end of the shell, or that portion within the engine cylinder is of special formation, and is'equipped with a pair of pockets or chambers 10, each having a restricted opening or mouth 11. The mouths open through the lower edge of the wall of the shell and the pockets or chambers eX- tend upwardly in the wall of the shell, increasing in area from the restricted mouth as best seen in Figure 2. The two chambers are located in diametrically opposite positions at the sides of the electrode of the spark plug, and as seen in Figure 3, these chambers are annular spaces extending circumferentially around the shell wall with the walls of the chambers diverging from the opposed ends of the openings or mouths 11, thus materially increasing the interior area of the chambers, as they approach their upper or inner closed ends.

At or near the inner ends of the chambers 10, the shell is transversely bored, from the outside to form a threaded socket 12, 12, one at each side of the shell and each opening into a chamberv or fp ocket '10. Either one' of these'duplexfsockets may'v-be utilized as required, the one not being-usedv cock 14, provided with a fiber handle 15 and an elbow or pipe bend 16, the latter threaded into the socket and opening into the inner end of the pocket or chamber 10 of the shell in Figure l, and thus establishing communication between the interior of' the cylinder and the cock.

By turning the handle 15 of the cock a portion of the gas from the cylinder may be permitted to pass therethrough to the atmosphere, and the gas or vapor emitted from the cock is subjected to inspection. By this inspection the quality of the fuel mixture within the cylinder may be ascertained,l and if necessary the mixture may be changed to rectify undesired conditions and increase the explosive effect of ignition. The compression of the mixture may also be'determined by the velocity of the gas escaping through the test cock, and other conditions existing within 'the cylinder may also be. ascertained, as for instance whether the spark is weak or strong, and with this knowledge proper action may be takento correct, change, or rectify the existing conditions to enhance the eiiciency of the engine.

The function of the auxiliary chambers 10 is to create a delayed, miniature, explosion of fuel gas to provide a blast of lgas past the electrodes and the lower end of the spark plug thus preventing accumulation of carbon at this point. Upon the compression stroke of the piston, a charge of gas is forced through the restricted mouths of the chambers 10, with the result that when the charge in the cylinder is ignited the explosion is conveyed or transmitted to the interior of these chambers and a delayed explosion occurs in these chambers. The blast from the explosions within the chambers results in a rush of gases through the restricted mouths of the chambers, directed toward.

the cylinder and past the electrodes and adjacent parts of t e spark plug and shell.

These blasts of gas prevent accumulation orI at the right lodging of carbon on the electrodes, thus maintaming them in a clean condition best adaptedfor eiiicient sparking. The scavenging stroke of the piston, by suction, withdraws and expels the burnt gases from the chambers, the fresh fuel is supplied to the chambers simultaneously with the charge to the cylinder.

By means of the test cock gas may be taken from the cylinder of the engine in the immediate vicinity of the electrodes or spark plug points 8 and 9, for testing, as for example, if the cylinder is firing properly, when the test cock is opened a puff of gas will be forced out on the compression stroke of the piston up through the chamber 10 and thence through the test cock 14, and the noise of the puff will be audible. When the ignition and explosioin take place in the cylinder a second blast or puff will occur, if all is well; if the second blast does not occur, it will be apparent that the cylinder is not firing, and lwhen the. diiierent cylinders of the engine are tested se arately the location of the trouble may quick y be determined. The test cock must not be opened too wide, as the inrush of air, due to suction at the time of' the suction stroke of the pistion, may cause the mixture of gas about the spark plug to be too lean with consequent misfiring.

Having thus fully described my invention, what claim as new anddesire to secure by Letters Patent is- The combination with a spark plug and its attaching shell formed with an inner bore surrounding lthe sparking end of the plug, said shell having a chamber in its wall formed with a restricted mouth opening into the engine cylinder and adapted to receive an explosive mixture whereby a blast of gas occurs past the sparking end of the plug with an explosion in said chamber.

In testimony whereof I aix my signature.

HoLLEY CARTMILL. 

